Thaw is a period in which the temperature rises above zero, snow and ice begin to melt slowly. We associate this time mainly with soaked shoes, muddy streets and flood hazard. Even a few warmer days can make a frozen surface of a river or lake thinner and more susceptible to cracks, which unfortunately is associated with serious accidents, especially among children sliding on its surface. Over time, a mass of drifting ice floes will remain on the surface of the river.